论文标题

单位圆和实际线上的正交多项式之间的CMV连接

A CMV connection between orthogonal polynomials on the unit circle and the real line

论文作者

Cantero, M. J., Marcellán, F., Moral, L., Velázquez, L.

论文摘要

M. Derevyagin,L。Vinet和A. Zhedanov在约束中引入。大约36(2012)513-535单位圆和实际线上的正交多项式之间的新连接。它根据真实参数$λ$将任何真实的CMV矩阵映射到Jacobi。这些作者证明,这张地图在单位圆圈上的雅各比多项式与实际线上的小$ -1 $ -1 $ -1 $ -1 $ -1 $ -1 $ -1。他们还提供了与雅各比矩阵相关的度量和正交多项式的明确表达式,而与cmv矩阵有关,但仅适用于$λ= 1 $的值,从而简化了连接 - 基本的DVZ连接 - 。但是,丢失了针对$λ$的任意值的类似的明确表达式 - 丢失了DVZ连接。这是本文克服的主要问题。 这项工作为DVZ连接引入了一种新方法,该方法通过使用CMV矩阵的已知属性将其作为二维本本征函。这使我们能够进一步发展,从而为一般DVZ连接提供了措施和正交多项式之间的明确关系。事实证明,该连接将单位圆的度量映射到一个在实际线的两个对称间隔上支持的偶数测量的有理扰动,这将减少到基本DVZ连接的单个间隔,而扰动变为一个多项式。 DVZ连接的某些实例显示出在真实线上为正交多项式的新的单参数家族。

M. Derevyagin, L. Vinet and A. Zhedanov introduced in Constr. Approx. 36 (2012) 513-535 a new connection between orthogonal polynomials on the unit circle and the real line. It maps any real CMV matrix into a Jacobi one depending on a real parameter $λ$. These authors prove that this map yields a natural link between the Jacobi polynomials on the unit circle and the little and big $-1$ Jacobi polynomials on the real line. They also provide explicit expressions for the measure and orthogonal polynomials associated with the Jacobi matrix in terms of those related to the CMV matrix, but only for the value $λ=1$ which simplifies the connection -basic DVZ connection-. However, similar explicit expressions for an arbitrary value of $λ$ -- (general) DVZ connection -- are missing. This is the main problem overcome in this paper. This work introduces a new approach to the DVZ connection which formulates it as a two-dimensional eigenproblem by using known properties of CMV matrices. This allows us to go further, providing explicit relations between the measures and orthogonal polynomials for the general DVZ connection. It turns out that this connection maps a measure on the unit circle into a rational perturbation of an even measure supported on two symmetric intervals of the real line, which reduce to a single interval for the basic DVZ connection, while the perturbation becomes a degree one polynomial. Some instances of the DVZ connection are shown to give new one-parameter families of orthogonal polynomials on the real line.

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